Gardo



H. R. RICARDO.

INTERNAL COIVIBUSIIONENGINE. APPLICATION FI'LED APR-23.1918.

II ,3 1 5,0371 Patented Sept. 2, 1919.

4 SHEETSSHEET I.-

I I I I I I H. R. RICARDO.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED APE-23.19112.

1 3 1 5 O 3 7 Patented Sept. 2, 1919.

4 SHEETS SHEET 2.

F/GZ.

H. R. RICARDO.

INTERNAL COMBUSTION ENGINE.

APPLICATION man APR.23.1918.

T. ,3 1 5,037. Patented Sept. 2,1919,

4 SHEETS-SHEET 3.

H. R. RICARDO.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED APR.23. 1918.

1 ,3 1 5M3? Patented Sept. 2, 1919.

4ISHEETSSHEET 4.

6 0 B f V i E HARRY RALPH RICARDO, or LONDON, ENGLAND.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed April 23, 1918. Serial No. 230,356.

To all whom it may concern: 1

Be it .known that I, HARRY RALPH RI oAnno, a subject of the King of England, and residing at London, in England, have invented certain new and useful Improvements in Internal-Combustion Engines, of which the following is a specification.

This invention relates to internal combustion engines operating on the two-stroke cycle and has for its object to efi'ect certain improvements in the scavenging and cooling of the cylinders.

W'hen usingair scavenging in engines of this type two difiiculties tend to arise. In the first Place the cooling that should be due to a scavenging charge of cold air is not actually fully realized because the air on entering the cylinder combines with the G0 which is always present to a greater or less eX- tent especially in petrol engines and the immediate result of this combination is to raise the temperature ofthe air to a considerable extent. This destroys the value of this air as a cooling agent and at the same time raises the initial temperature of the charge before compressionf Secondly the whole of the air required for scavenging has to be supplied under a pressure sufficient to overcome the exhaust back pressure and also the resistance offered by the ports, valves and passages. Also the quantity of airrequired for efl'ective scavenging is large and the power which must be employed to supply this air under pressure represents an appreciable proportion of the total power of the engine. The actual quantity of air needed for effective scavenging and cooling is greatly in excess of that required for the I combustible charge since a considerable proportion of the-scavenging charge is inevita'bly lost through the exhaust ports and some at least of the remaining air is required as a diluent.

The object of the present invention is to provide a simple means whereby the scavenging and cooling of the cylinder may be accomplished by cooled exhaust gases the relcascd pressure of these gases being uti lizcd for the purpose so that the scavenging pump can he reduced in size or cvcn clumnatcd. By thus employing coolcd cxhausr. gasc'sthc internal cooling of the cylinder is appreciably improved .\'lll thcsc gases are inert and after-burning cannot occur. Furthcr if they are thoroughly coolcd. cxhanst gases are preferable to air as forming the diluent portion of the charge since the presence of CO has the advantage that it both raises the self-ignition temperature of the fuel and prevents unduly rapid burning. By thus utilizing cooled exhaust gases the whole of the scavenging of the hot exhaust products and the cooling of the cylinder can be accomplished without absorption of useful power developed by the engine and work need only be done in compressing and dclivering the relatively small amount of fuel and air required to form the combustible charge.

According to this invention the cylinder of an internal combustion engine operating on the two-stroke cycle has an exhaust port leading to the atmosphere positioned in the length of the cylinder where it will be uncovered by the piston at the end of its outstroke and a second port positioned in the length of they cylinder where it willbe nucovered by thepiston on its out/stroke at or about the time when the first exhaust port is uncovered. A chamber of substantial capacity in relation to the cylinder is provided together with one or more cooled passages which constitutes a free communication between the second port and the chamber. On the outstroke of the piston the port leading to the chamber is uncovered and the prod- .ucts of combustion are discharged at high pressure through this port and through the cooled passage or passages into the chamber where the cooled gases are temporarily stored under pressure. The main exhaust port is uncovered as the piston completes its outstroke and the remaining products of combustion are discharged to the atmosphere. When as a result of the escape of these products of combustion to the atmosphere the pressure in the cylinder falls below that of the gases stored in the separate chamber and in the cooled passages leading thereto, these cooled gases pass back into the cylinder and drive out the residue of the highly heated exhaust products at the same time cooling the piston and the cylinder walls. Under certain circumstances it may be found desirable to deliver a certain amount of air to the chamber in such a manner that this air will follow the cooled exhaust products into the cylinder. In this way a portion of the air required for tho cmuhustihlc c large may he admitted through the same port as tho scavenging charge of epoled exhaust gases. The combustible charge is forced into, the cylinder through a separate valve controlled port, preferably.

situated as far as possible from the exhaust port, either during the scavenging period or after this scavenging period the introduction of this combustible charge being effected if desired in a manner so as to supercharge the cylinder. The introduction of the combustible charge may be brought about by means of a pump or in some other manner commonly employed in two-cycle engines such for example as by crank case compression.

The accompanying drawings illustrate by way of example constructions of internal combustion engine in which the present invention is embodied.- In these drawings,

Figure 1 is a' sectional elevation of one cylinder of a' multicylinder internal combustion engine constructed and arranged to operate in accordance with this invention.

Fig. 2 is a similar view through the cylinder of the same engine the section however being taken at right angles to the plane of the aper in Fig. 1.

Fig. 3 is an end elevation of the complete engine having each of the four cylinders constructed as shown in Figs. 1 and 2 and embodying the present invention.

Fig. 4 1s a diagrammatic sectional elevation of an engine to which the invention is applied in a modified form.

Like letters indicate like out the drawings.

Referring to'the construction illustrated in Figs. 1, 2 and 3 each cylinderA of the engine is provided toward its outer end with ports B leading to a passage B through which the exhaust gases can escape to the atmosphere. These ports B are positioned where they will be uncovered by the piston C at or about the end of its outstroke. Other and conveniently similar ports D are formed in the wall of the cylinder A and p0- sitioned preferably opposite to the ports B where they also will be uncovered by the piston C at or about the end of its outstroke. These ports D open into one end of a passage D at the other end of which is a tube plate carrying a series of tubes E around which water can circulate in a chamber F through which these tubes E pass. The tubes E constitute a cooled passage which opens into a chamber G whence a parts throughpipe G leads to a blower or other air pump.

The piston C has a long skirt or trunk C in which is formed a port C adapted to register with a similar port A formed in the wall of the cylinder A toward its outer end. This port opens into a passage A whence runs a pipe H to the annular inlet passage J formed in or on the head of the next adjacent cylinder. From this annular inlet gases can enter the cylinder through ports J controlled by a non-return valve in the drawings controls the inlet M.

K of the leaf type which is constructed and arranged in a known manner.

The piston preferably employed is of a' the outer end of this projection C is mounted a cylindrical guide member C which carries the gudgeon pin and reciprocates in a guide cylinder L. The latter projects into the outer end of the main cylinder A. a pump chamber M being formed between the outer wall of the guide cylinder L and the interior of the outer end of the main cylinder A or a prolongation thereof which may be constituted by a part N of the water jacket. The annular part of the head of the piston C between the hollow projection C and the skirt C-'constitutes a pump'serving to compress combustible mixture drawn into the annular pump chamber M.

The cooling chamberor jacket F which incloses the pipes E is conveniently placed in communication as at F with the cylinder water acket.

- The engine operates as mentioned on the two-stroke cycle and in the following manner: On the outstroke of the piston C, combustible mixture is compressed into'the annular pump chamber M, this mixture having been drawn into this chamber on the inlet M (Fig. 2) from an annular chamber 0 into which the induction pipe 0 (Fig. 3) leads tangentially from the carbureter P. A suitable non-return valve not shown As the piston C nears the end of its outstroke the port C registers with the port A" and the combustible mixture under pressure flows from the pump chamber M of one cylinder to the inlet J of the next adjacent cylinder.

Shortly before the piston C completes its outstroke the ports D. are uncovered and some of the products of combustion from the cylinder A How through the ports D into the passage D and thence'through the cooled pipes E into the chamber G. Simultaneously or immediately afterward, if the ports D happen to be set so as to be uncovered slightly in advance of the uncovering of the ports B. the ports B are uncovered by the piston and other products of combustion escape through the passage B to the atmosphere. Air is constantly supplied under pressure through the pipe G to the chamber G and since the pressure in the of the exhaust ports B just after some of and partly by the action of the air. The

interior of the cylinder will thus be scavenged by these cooled products of combustion followed by some air which will sweep the hot products of combustion out of the cylinder through the exhaust ports B. As

the piston C will now have commenced its instroke some portion of these cooled prod nets of combustion will be trapped in the cylinder together with some of the pure air which has followed these cooled proucts of combustion into the cylinder from the chamber G. At this moment the charge of combustible mixture under pressure will enter the head of the cylinder through the inlet ports J pastthe valve K, this combustible mixture being delivered from the pump chamber M of the next adjacent cylinder. The piston then performs its compression stroke duringwhich the port A will be covered by the skirt C of the piston and a fresh charge of combustible mixture will be drawn into the pump chamber M through the inlet M.

The blower used may be of any well known type, and may be used in the case of single cylinder engines as well as multicylider engines. It the blower is of the centrifugal type it will supply air until the pressure in the passage has reached three or four pounds per square inch after which it will cease delivering air. If the blower is of the positive type a chamber having such capacity will be provided between the blower and the cylinder to prevent the air pressure becoming excessive. It will be seen that the pressure of the exhaust gases when the ports are firstopened is about or pounds per square inch or greatly in excess of the air pressure existing in the passage. After the exhaust ports are open fully the pressure will drop to two or three pounds per square inch in the cylinders and the gases exhausted previously into the passages will fiow back into the cylinder and will be followedby the air from the blower.

The invention may be otherwise applied in various ways to difi'erent types of twostroke engines, an example of such an appli cation being given diagrammaticaly in Fig; l.

Fig. -l illustrates a simple internal combustion engine having one or more cylinders A which are separate from each other in that they do not communicate, the main inlet J for the combustible charge terminates in a port disposed in the head of the cylinder and constructed and arranged with a valve such as K controlling it in some convenient manner. At one side of the cylinder A and so positioned in the length thereof as to be uncovered by the piston C toward the end of its outstroke there are formed one or more ports I) which open into a passage D which leads to a series of cooled tubes E arranged t'or example as in the construction shown in Figs. 1 and 2. In this case, however, the chamber G in to which thecooled tubes E lead isa closed chamber of suitable form and capacity. Preferably this chamber is as shown of bulb or pear shape and its capacity is equal or greater than the cylinder volume. In some cases it may-be desirable to use a chamber of large capacity. The wall of this chamber G may or not be cooled as found desirable. The passage D between thecooling pipes E and the ports D is preferably tapered or is somewhat constricted as in the corresponding passage in the engine illustrated in Fig. 1 so that the gases passing through this passage will tend to acquire an increased velocity more especially when after being cooled in the tubes E these gases reenter the cylinder A. Exhaust ports B leading to a passage B opening into the atmosphere are formed in the wall of the cylinder A opposite to the ports D so that these ports B will be uncovered by the piston C just as it reaches the end of its outstroke.

In operation, toward the end of the working stroke of the piston Cthe ports i) will be uncovered and the products of combustion will pass under pressure from the cylinder A through the ports I) and passage D and through the water-cooled tubes E into the closed chamber G. The exhaust ports B being uncoveredby the piston C simul taneously with or almost immediately after the ports D, some portion of the products of combustion escape through the ports B to the atmosphere. When the pressure in the cylinder A has fallen owing to the escape of these exhaust gases those products of combustion which have entered the closed chaml 0 ber G and have been cooled in their passage through the pipes E return into the cylinder A and sheet scavenging thereof. Some portion of these cooled products of combustion are trapped in the cylinder when the piston C on its return stroke covers once more the ports B and D. I

The details of construction may be varied in accordance with requirements. As indi cated either one or more ports such as D may be provided leading from the cylinder to the chamber G and similarly more than one exhaust port may be employed. The construction of the chamber G where this chamber is completely closed as in the example illustrated in Fig. 4 or where air is delivered into this chamber as in the construction illustrated in Figs. 1 and :2 may be modified as found desirable. The cooled passage or passages E may also be constructed in various ways as for instance in place ofthe gases being led through separate pipes such as E around which water circulates in the manner illustrated in Figs. 1 and 2, these gases may pass to the chamber G through a chamber or passage in which are a series of pipes through which water is circulated. The shape and disposition of the cooling passage E as also the passage D" leading thereto andthe chamber may vary as found desirable.

It is to be noted that in applying the present improvement to internal combustion engines of either of the types indicated for example in Fig. 4 no material alteration of such engines is called for; It is also a feature of the present improvement that no valve is required or employed to control either the passage of the products of combustion into the chamber G or the return of these gases into the cylinder and the construction and operation of the engine is therefore simplified in that there is no necessity to provide means for the cooling of such valves which would otherwise tend to become overheated.

What I claim as my invention and desire to secure by Letters Patent is 1. In an internal combustion engine operating on the two stroke cycle the combination of a cylinder, a piston reciprocating in this cylinder, an exaliust port in the wall of the cylinder leading to the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of the outstroke, a secondport in the wall of the cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when the first port begins to be uncovered, a separate chamber of substantial capacity in relation to the cylinder, a. passage constituting a free communication between this chamber and the second port in the cylinder wall so that when this port is uncovered by the piston some portion of. the exhaust gasesfrom the cylinder can pass freely through this passage into the chamber and return thence into the cylinder, and means for cooling the gases as they pass through this passage as set forth.

2. In an internal combustion engine operating on the two-stroke cycle the combination of a cylinder, a valve controlled port in the head of the cylinder, means for delivering combustible mixture under pressure into the cylinder through this port, a piston reciprocating in this cylinder, an exhaust port in the wall of the cylinder leading to the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its'outstroke, a second port in the wall of the cylinder positioned in the length of the cylinder where it will gases from the cylinder can pass freely through this passage into the chamber and return thence into the cylinder, and means for cooling the gases as they pass through this passage as set forth.

3. In an internal'combustion engine operating on the two-stroke cycle the combination ofa cylinder, a valve controlled port in the head of the cylinder through which combustible mixture is delivered into the cylinder, a differential piston reciprocating in the cylinder, an annular pump chamber formed at the outer end of the cylinder into which the piston draws a charge of combustible mixture and in which chamber this mixture is compressed, an exhaust port in the wall of the cylinder leading to the at mosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its working stroke, a second port in the wall of the cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when the first port begins to be uncovered, a separate chamber of substantial capacity in relation to the cylinder, a passage constituting a free communication between this chamber and, the second port in the cylinder wall so that when this port is uncovered by the piston some portion of the. exhaust gases from the cylinder can pass freely through this passage into the chamber and return thence into the cylinder, and means for cooling the gases as they pass through this passage as set forth.

4. In an internal combustion engine operating on the two-stroke cycle the combination of a cylinder, a piston reciprocating in this cylinder, an exhaust port in the wall of the cylinder leading to the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its outstroke, a second port in the wall of the cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when the first port begins to be uncovered, a separate chamber of substantial capacity in relation to the cylinder, means for delivering air into this chamber, a passage constituting a free communication between this chamber and the second port in the cylinder wall so that when this port is uncovered by the piston some portion of the exhaust gases from the cylinder can pass freely through this passage into the chamber and return thence into the cylinder together with air" from the chamber, and means for cooling the gases as they pass through this passage as set forth. 1

5. In an internal combustion engine operating on the two-stroke cycle the combination of a plurality of cylinders, a valve controlled port in the head of each cylinder,

means for delivering combustible mixture under pressure into; each cylinder through this port, a piston reciprocating in each cylinder, an exhaust port in the wall of each cylinder leading to: the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its working stroke, a second port in the wall of each cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when thefirst port begins to be uncovered, a plurality of separate chambers of substantial capacity in relation to the cylinders, passages constituting free communications between each one of these chambers and the second port in each of two adjacent cylinders between which each chamber is situated so that when these ports are uncovered by the pistons in the cylinders.some portion ofthe exhaust gases from the cylinders can pass freely into these passages and back into the cylinders, and means for cooling the gases as they pass through these passages as set forth.

6. In an internal combustion engine operating on the two-stroke cycle the combination of a plurality of cylinders, a valve controlled port in the head of each cylinder through which combustible mixture is delivered into the cylinder, a diiferential piston reciprocating in each cylinder, an annular pump chamber formed at the outer end of each cylinder into which the piston in that cylinder draws a charge of combustible mix- I ture and in: which chamber this mixture is compressed and whence it is delivered to the inlet port in the head of the next adjacent cylinder, an exhaust port in the wall of each cylinder leading to the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its working stroke, a second port in the wall of each cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when the first port begins to be uncovered, a plurality of separate chambers of substantial capacity in relation to the cylinders,

passages constituting free communications between each one of these chambers and the second port in each of two adjacent cylinders between which each chamber is situated so that When these ports are uncovered by the pistons in the cylinders some portion of the exhaust gases from the cylinders can pass freely through these passages into the chambers and return thence into the cylinders, and means for cooling the gases as they pass through these passages as set forth.

. 7. In an internal combustion engine operating on the two-stroke cycle the combination of a plurality of cylinders, a valve controlled port in the head of each cylinder through which combustible mixture is delivered into the cylinder, a diflerential piston reciprocating in each cylinder, an annular pump chamber formed at the outer end of each cylinder into which the piston in that cylinder draws a charge of combustible mixture and in which chamber this mixture is compressed and whence it is delivered to the inlet port in the head of the next adjacent cylinder, an exhaust port in the wall of each cylinder leading to the atmosphere and positioned in the length of the cylinder where it will be uncovered by the piston at the end of its working stroke,'a second port in the wall of each cylinder positioned in the length of the cylinder where it will be uncovered by the piston about the time when the first port begins to be uncovered, a plurality of separate chambers of substantial capacity in relation to the cylinders, means for delivering air into each of these chambers, passages constituting tree communications between each one of these chambers and the second port in each of two adjacent cylinders between which each chamber is HARRY RALPH RICARDO.

Witnesses ARTHUR JAMES HALL, R. BAooA'rr. 

